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Gravity Probe B is at NASA spacecraft processing hangar 1610 on North Vandenberg Air Force Base. In processing activities this week, the initial filling of the dewar with cryogenic helium has been performed. This prepared the dewar for the upcoming series of about 6 -7 cycles of pumping down the tank to a near vacuum, then refilling as necessary, to achieve the superfluid conditions. The first pump-down began on Wednesday, Sept. 3.

The electromagnetic interference (EMI) test and the Gas Management Assembly (GMA) "rate of rise" test were successfully finished as scheduled.

The erection of the Boeing Delta II launch vehicle at Space Launch Complex 2 remains scheduled to begin on Sept. 15 with the erection of the first stage. Attachment of the nine strap-on solid rocket boosters in sets of three is scheduled for Sept. 17-19. The second stage is planned for mating atop the first stage on Sept. 22. Gravity Probe B will be transported from the spacecraft hangar to Space Launch Complex 2 on Oct. 29 and hoisted atop the second stage. The Delta II fairing will be installed around the spacecraft on Nov. 5 as part of final preparations for launch.

Gravity Probe B arrived at Vandenberg Air Force Base on July 11 from the Lockheed Martin plant in Sunnyvale, Calif.

Gravity Probe B is a relativity experiment developed by NASA's Marshall Space Flight Center, Stanford University and Lockheed Martin. The spacecraft will test two extraordinary predictions of Albert Einstein's general theory of relativity that he advanced in 1916. Gravity Probe B consists of four sophisticated gyroscopes to be launched into a 400-mile-high orbit for a mission lasting 18 months.